﻿/*
* Metadata - jQuery plugin for parsing metadata from elements
*
* Copyright (c) 2006 John Resig, Yehuda Katz, Jörn Zaefferer, Paul McLanahan
*
* Dual licensed under the MIT and GPL licenses:
* http://www.opensource.org/licenses/mit-license.php
* http://www.gnu.org/licenses/gpl.html
*
*/

/**
* Sets the type of metadata to use. Metadata is encoded in JSON, and each property
* in the JSON will become a property of the element itself.
*
* There are three supported types of metadata storage:
*
* attr: Inside an attribute. The name parameter indicates *which* attribute.
*
* class: Inside the class attribute, wrapped in curly braces: { }
*
* elem: Inside a child element (e.g. a script tag). The
* name parameter indicates *which* element.
*
* The metadata for an element is loaded the first time the element is accessed via jQuery.
*
* As a result, you can define the metadata type, use $(expr) to load the metadata into the elements
* matched by expr, then redefine the metadata type and run another $(expr) for other elements.
*
* @name $.metadata.setType
*
* @example <p id="one" class="some_class {item_id: 1, item_label: 'Label'}">This is a p</p>
* @before $.metadata.setType("class")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from the class attribute
*
* @example <p id="one" class="some_class" data="{item_id: 1, item_label: 'Label'}">This is a p</p>
* @before $.metadata.setType("attr", "data")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from a "data" attribute
*
* @example <p id="one" class="some_class"><script>{item_id: 1, item_label: 'Label'}</script>This is a p</p>
* @before $.metadata.setType("elem", "script")
* @after $("#one").metadata().item_id == 1; $("#one").metadata().item_label == "Label"
* @desc Reads metadata from a nested script element
*
* @param String type The encoding type
* @param String name The name of the attribute to be used to get metadata (optional)
* @cat Plugins/Metadata
* @descr Sets the type of encoding to be used when loading metadata for the first time
* @type undefined
* @see metadata()
*/

(function ($) {

   $.extend({
      metadata: {
         defaults: {
            type: 'class',
            name: 'metadata',
            cre: /({.*})/,
            single: 'metadata'
         },
         setType: function (type, name) {
            this.defaults.type = type;
            this.defaults.name = name;
         },
         get: function (elem, opts) {
            var settings = $.extend({}, this.defaults, opts);
            // check for empty string in single property
            if (!settings.single.length) settings.single = 'metadata';

            var data = $.data(elem, settings.single);
            // returned cached data if it already exists
            if (data) return data;

            data = "{}";

            if (settings.type == "class") {
               var m = settings.cre.exec(elem.className);
               if (m)
                  data = m[1];
            } else if (settings.type == "elem") {
               if (!elem.getElementsByTagName)
                  return undefined;
               var e = elem.getElementsByTagName(settings.name);
               if (e.length)
                  data = $.trim(e[0].innerHTML);
            } else if (elem.getAttribute != undefined) {
               var attr = elem.getAttribute(settings.name);
               if (attr)
                  data = attr;
            }

            if (data.indexOf('{') < 0)
               data = "{" + data + "}";

            data = eval("(" + data + ")");

            $.data(elem, settings.single, data);
            return data;
         }
      }
   });

   /**
   * Returns the metadata object for the first member of the jQuery object.
   *
   * @name metadata
   * @descr Returns element's metadata object
   * @param Object opts An object contianing settings to override the defaults
   * @type jQuery
   * @cat Plugins/Metadata
   */
   $.fn.metadata = function (opts) {
      return $.metadata.get(this[0], opts);
   };

})(jQuery);